Hydraulic weighing scales



P 1950 R. s. BOHANNAN 2,523,413

mmmuuc wmcnmc SCALES Filed Dec. 6, 1945 2 Sheets-Sheet l Babe/"7 J.50/70/7/70/7 Fig. I

KTTORNEYS p 1950 R. s. BOHANNAN 2,523,413

HYDRAULIC wmcnmc SCALES Filed Dec. 6, 1945 2 Sheets-Sheet 2 x s Tm-E 2I. 3/

a IN V EN TOR.

I Babe/"7 J. 15aha/7/70/7 ATTORNEYS Patented Sept. 26, 1950 2,523,413HYDRAULIC WEIGHING scams Robert S. Bohannan, Toledo, Ohio, assignor toToledo Scale Company, Toledo, Ohio, a corpo ration of New JerseyApplication December 6, 1945, Serial No. 633,200

This invention relates to weighing scales employing hydraulic forcetransmitting elements and in particular to an improved mounting for thehydraulic capsules serving as supports for the load receiver.

One of the diiliculties encountered in the construction of a precisionweighing scale employing hydraulic force transmitting elements is theelimination of the error introduced by tipping of the plates of thehydraulic capsules serving as load supports. When one part of a capsuletips with respect to the other part a small change in efiective areaoccurs. This apparent change in efiective area of a capsule has beenobserved in those capsules in which a flexible membrane is used toconfine the hydraulic fluid. When one part of the capsule tips the widthof the space sealed by the membrane is slightly increased. The effectivearea of the capsules before any tipping occurs includes half of theprojected area of the membrane. When tipping occurs and the width of thespace sealed by the membrane increases half of the increase is takenfrom the effective area of the capsule because half of the membrane issupported from the fixed plate of the capsule. Thus, the tipping causesan apparent decrease in the effective area of the capsule and for agiven load results in slightly higher hydraulic pressure.

The tipping of a capsule may be caused by the bending of the girderssupporting the platform of the scale when a concentrated load is placedon the center of the platform or it may be caused by side forces tendingto laterally displace the platform.

The principal object of this invention is to provide an improvedmounting for a hydraulic capsule such that the capsule elements will notbe deranged by either lateral movement of the platform or deflection ofthe girders of the platform.

Another object of the invention is to provide a mounting for a hydrauliccapsule such that eccentric loading of the capsule is prevented.

Another object is to provide a simple structure for supporting aweighing scale load receiver which structure will permit oscillation ofthe load receiver but will prevent any tipping of the capsule elementswith respect to each other.

These and other objects and advantages are attained according to theinvention by utilizing a hydraulic capsule as a link of a suspensionsystem serving as a support for the load receiver of a scale. By formingthe capsule assembly so that it may be used as a freely swinging link ofa suspension system the capsule assembly is sub- 4 Claims. (Cl. 265-47)jected only to tensile forces and therefore all tendency for the capsuleelements to tip with respect to each other is eliminated.

A specific embodiment illustrating a preferred form of the invention isillustrated in the drawings.

In the drawings:

Figure I is a side elevation, partly in section, of a hydraulic weighingscale in which the load receiver is supported on hydraulic capsulesmounted according to the invention.

Figure II is a plan view, partly in section, of the weighing scale shownin Figure I.

Figure II is a side elevation at greatly enlarged scale of one of thehydraulic capsules serving as a support for th load receiver.

Figure IV is a plan view, with parts broken away and parts shown insection, of the hydraulic capsule shown in Figure III.

These specific figures and the accompanying description illustrate apreferred form of the invention and are not intended as limitations onthe claims.

A hydraulic weighing scale constructed according to the inventionconsists of a load receiver I having a, deck '2 made of wood or othersuitable material supported on a rigid steel girder structure 3. At eachcorner of the load receiver I the steel framework 3 is provided with alaterally extendin bracket 4 which is suspended from a hook 5 by acapsule assembly 6 serving as ,a freely swinging link. The hooks 5 areset in overhanging steel copings I defining the edge of a concrete linedpit.

Hydraulic pressures generated in the capsule assemblies 6 in response toloads placed on the load receiver I are transmitted through pipes 8 topressure receiving elements 9 mounted on a bracket I!) attached to thelower surface of a weigh beam shelf II. Bellows mounted within thepressure receivers 23 act against struts I2 to transmit force throughthe struts I2 to load knife edges I 3 of a gathering lever I4. There isa pressure receiver 9 and strut I2 for each of the capsule assemblies 6located at the corners of the load receiver I. The gathering lever I4 isfulcrumed on bearings I5 mounted in the lower end of an arm of thebracket ID. The lever I4 is provided with a power pivot I6 which,connected through stirrups I1 and a steelyard rod I8, transmits force toa load knife edge I9 fitted in a weigh beam 20'. The weigh beam 20 isfulcrumed on a pedestal 2| erected from the beam shelf -I I. A poise 22slidably mounted on the weigh beam 20 serves to counterbalance forcesapplied to the position. The plate 24 is horizontal when the beam is inuse.

The gathering lever l4 and the pressure receivers 9 are enclosed in acabinet 28 formed integrally with a pedestal 29 serving as a support forthe weigh beam shelf II.

The capsule assembly is shown in detail in Figure III. The capsuleitself consists of a lower plate 30 whose upper surface is relieved toform a"chamber" 3l aclapted to contain hydraulicfluid. The hydraulicfluid :is confined by a; membrane 32 formed of a sheet ofrubberionotherrffiexible material and clamped to the 'peripherymf "theplate Sil 'by "-a sealing ring :33 :held; in :place by -a plurality ofscrews 34. A diaphragm or upper capsule plate 35 rests on thetmembrane"32,ithe membrane'rbeing allowedto'tlform a bead :36 in 'the spa cebetween the peripher zofrthe diaphragm 35' and the olamping ring :33.The hydraulic fluid in the-chambe'rISI serves toxsupport the diaphragm35 and, b communicationlthrough'the pipes S, to transmit any load forcesapplied to-the diaphragm 35 to the pressure "receivers '9 which act-'o'n"the gathering lever M. 'Loa d". forces are applied to thediaphragmi-35'b ardouble hook or 'c -shaped member 3! whose'ends arebolted to'the 'diaphragm"35 and which extends around-theedge of andbelow the lowerplatef30 of the capsule. The center'oftthe'lower'part.ofthe oeshaped memberfi'i is provided witlr-aneye '38 engaged by a Ubolt'IS-S. ZTheen'dsof'the u-bolt pass through holes 40 in the bottomfiangenof the bracket A and are threaded .to receivenuts 4| so that the:bracket 4 imay be. supported from the 'C-shaped'member13'i. ,A similarC-shape'd membenziZ :whose-ends'are bolted to the lower cap- "'suleplate :3='1 exte'rrdsacross .the 'top of the capsulez'assembly andinits'zupper center-section is .prox' ided-withl'anreye 4'3'adaptedto-receive the book 5.

:The%eyes':38'and' 43 are beveled outwardly each -Way so thatsubstantially :point contact is made with the U-bolt 39 and the hook 5;"iiIn thisfconstruction: since the load and sup- :portingforces aretransmitted tozthe capsuleiassembl through 'thesubstantially pointcontacts Qin' 'the -eyes' 38 and431the vcapsulezassembly .6 :behaves'asrthough it were a: link of-achain coninectingthe U-bolt'39to thehook-5. Therefore,

imembersufia and 331 :respectively: so that neither ofthe platesimay tipwith respect to C shaped imembers and thereby cause the :relativetipping cf :the capsule plates. Themembrane-32 is sufficiently stronginshearrso-that the diaphragm -3 5-+the upper :member ofthe-:capsule-ecannot :slide TOff rsidewise. Y .,-This'.-constructionprovides'isimple means for .insuring thationly straightcompressiveforees free 4 from any tipping or bending are transmitted tothe diaphragm of the hydraulic capsule and therefore the hydraulic forcetransmission ratios of the capsules are not affected by any swinging ofthe load receiver I or any deflection of the desk supporting framework3.

The preferred structure for employing a hydraulic capsule as a forcemeasurin element in a suspension system is shown inthe. drawings. Theassembly may be varied in various details of either capsule constructionor bracket arrangement without losing the benefits obtained by employingthe capsule assembly as a tension member subjected'to tensile forcesonly and permitting it"to-alignitselfwith the line of action of the"forces which it is designed to translate into hydraulic pressure.

Having described the invention, I claim:

.1. In a weighing scale, in combination, a load receiver, a framesurrounding the load receiver, .a; plurality of; links dependinglyattached to @the frame: a plurality of ;links .attached. to portions.of. the'load receiverthat are. located. beneath the frame. links and aplurality. of hydraulic. capsules equipped with means forengagingthelinks to swingably support .the load receiver from -.theframe.

-2. In a weighing scalehin combination, a load receiver, a framesurrounding the loadreceiver with portions of the. frameoverhangingportions of the load receiver, links dependingfrom theoverhanging portions of the frame, .otherllinks mounted in, the overhungportionsof the. load re- .ceiver,. and ,p1urality of hydraulic capsulessuspended from .the l depending links, and connected to the loadreceiver; links, the .assemblies comprising'the. capsules and,linksserving as the ,sole support foiuthecload receiver.

3. In a weighing scale,.in combination a load receiver, a framesurrounding theload receiver, support members dependingly attached tothe frame, other members on the'load receiverthat are'located beneaththe support members, and a plurality .of hydraulic capsulesequipped with:means for en aging the members .to swingably support the'load receiverfrom the frame.

Y 4. In a weighing scale,.in 'combination, a load receiver, a framesurrounding the load receiver with portions of the frame overhangingportions of the load receiver, depending supports on'.the frame,supportmembers mounted in the,lo ad receiver, and a plurality of hydraulicoapsulessuspended from .the depending. supports and connected to theload receiver .members, .the support assemblies including the capsulesservingas the solesupport forthe load-receiver.

RQBERT ,S. BOHANNAN.

REFERENCES CITED The following references are .ofsrecordl .the file ofthis patent:

V "'UNrrEnsTATEsP 'rE Ts Numb er I "1323s "Great Britain -1913

